Different firing modes or frequencies occur in the brain and/or other neuronal tissue, for example tonic firing and burst firing (irregular or regular burst firing). Such firing modes can be utilized for normal processing of information, however, alteration of the firing modes, may also lead to pathology.
For example, certain neurological conditions are associated with hyperactivity of the brain and can be traced to a rhythmic burst firing or high frequency tonic firing or hypersynchronous firing (e.g., tinnitus, pain, and epilepsy). Other conditions can be associated with an arrhythmic burst firing or a dysynchronous firing, for example, movement disorders, hallucinations, persistent vegetative state (PVS), multiple chemical sensitivity (MCS), or hypofunctioning for example, hypoesthesia, depression, hearing loss, visual loss, dysthymia, chronic fatigue etc.
During the past decade, neuromodulation systems have been used to modulate various areas of the brain, spinal cord, or peripheral nerves (See, for example, U.S. Pat. Nos. 6,671,555; 6,690,974). These types of systems utilize tonic forms of electrical stimulation. Recently burst transcranial magnetic stimulation (TMS) at theta frequencies has been developed (Huang et al., 2005). Theta burst TMS has been shown to produce an effect on motor and visual cortex by suppressing excitatory circuits after a short application period of only 20-190 s (Huang et al., 2005; Di Lazzaro et al., 2005; Franca et al., 2006).
Typically, the signals generated by the neuromodulation devices are not physiological similar to the endogenous electrical signals generated by the brain and the exogenous electrical signals generated by the neuromodulation devices typically result in epileptic events as well as the brain habituates to these electrical signals in time. The inventor is the first to describe a neuromodulation design using parameters in which a 1/fβ noise is used to achieve stimulation of the tissue close to physiological levels to treat a neurological condition.